Portable holding tank



FIG. 1 is a front perspective view of a portable holding tank showing our new design.

FIG. 2 is a front view thereof.

FIG. 3 is a rear side view thereof.

FIG. 4 is a right view thereof.

FIG. 5 is a left side view thereof.

FIG. 6 is a bottom view thereof; and,

FIG. 7 is a top view thereof.

It will be understood that the broken lines shown throughout the drawings are for illustrative purposes only and form no part of the present invention. 

The ornamental design for a portable holding tank, as shown and described. 